Package film tension adjusting device of packaging machine

ABSTRACT

A packaging machine includes a supply of a package film and a wrapping/sealing section into which products to be packaged are conveyed. A package film tension adjusting device is arranged between the supply of the package film and the wrapping/sealing section for routing the package film to the wrapping/sealing section and for adjusting the tension of the package film supplied to the wrapping/sealing section. The package film tension adjusting device includes a chassis inside which two rails are fixed. Two slide blocks are movably supported on the rails and are movable toward/away from the wrapping/sealing section along the rails. A conveyor is supported on the slide blocks for conveying the products into the wrapping/sealing section. Film routing members are attached to the conveyor for routing the package film toward the wrapping/sealing section. Moving the slide blocks along the rails causes the distance between the film routing members and the wrapping/sealing section to be changed thereby changing the tension of the package film supplied from the film routing members to the wrapping/sealing section in a stepless manner. A locker unit is mounted to at least one of the slide blocks for releasably securing the slide block at a desired position along the rails. A screw rod threadingly engages the slide blocks for moving the slide blocks along the rails.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to a packaging machine, and in particular to a device for adjusting the tension of a package film supplied into the packaging machine for packaging a product.

[0003] 2. The Related Art

[0004] Plastic films have been widely used to wrap and pack consumer products, such as foods, books, video/audio compact disks for protecting the products from contamination and damage. A packaging machine is required to warp the package film around the product. The package film that is wrapped around the product is then heated along sealing line to seal the package film around the product so as to completely enclose the product with the package film.

[0005] The package film is commonly supplied in the form of a roll whereby the package film is unwound and supplied from the roll in a continuous manner. Due to the potential difference between the speed of the package film unwound from the roll and the speed by which the products to be packaged are conveyed, the package film may be over-tensioned or under-tensioned, resulting in poor quality of packaging. When the package film is over-tensioned, the product wrapped by the package film may undergo undesired deformation. In addition, the sealing line may not be able take the tension and thus break. When the package film is under-tensioned, the product cannot be properly wrapped and protected.

[0006] Thus, it is desired to have a package film tension adjusting device for properly tensioning the package film in a package machine so as to overcome the above problems.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide a package film tension adjusting device for a packaging machine wherein the tension of the package film fed into the packaging machine is properly adjusted.

[0008] Another object of the present invention is to provide a package film tension adjusting device that allows a stepless adjustment of the film tension that is fed into a packaging machine.

[0009] A further object of the present invention is to provide a package film tension adjusting device comprising a locker unit to secure the adjusting device in a desired position to maintain the tension of the package film supplied to a packaging machine.

[0010] To achieve the above objects, in accordance with the present invention, there is provided a package film tension adjusting device adapted to be arranged between a supply of a package film and a wrapping/sealing section of a packaging machine. The package film tension adjusting device includes a chassis inside which two rails are fixed. Two slide blocks are movably supported on the rails and are movable toward/away from the wrapping/sealing section along the rails. A conveyor is supported on the slide blocks for conveying products to be packaged into the wrapping/sealing section. Film routing members are attached to the conveyor for routing the package film toward the wrapping/sealing section. Moving the slide blocks along the rails causes the distance between the film routing members and the wrapping/sealing section to be changed thereby changing the tension of the package film supplied from the film routing members to the wrapping/sealing section in a stepless manner. A locker unit is mounted to at least one of the slide blocks for releasably securing the slide block at a desired position along the rails. A screw rod threadingly engages the slide blocks for moving the slide blocks along the rails.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which:

[0012]FIG. 1 is a perspective view of a packaging machine in which a package film tension adjusting device constructed in accordance with a first embodiment of the present invention is incorporated;

[0013]FIG. 2 is a perspective view of the package film tension adjusting device of the present invention;

[0014]FIG. 3 is an enlarged view of a locker unit of the package film tension adjusting device of the present invention;

[0015]FIG. 4 is a top view of the package film tension adjusting device of the present invention showing a film tension adjustment operation carried out thereby;

[0016]FIG. 5 is a perspective view of a package film tension adjusting device constructed in accordance with a second embodiment of the present invention; and

[0017]FIG. 6 is a perspective view of a package film tension adjusting device constructed in accordance with a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] With reference to the drawings and in particular to FIG. 1, a packaging machine, generally designated with reference numeral 200, comprises a film supply section 210 from which a package film A in the form of a roll is continuously supplied and a wrapping/sealing section 220 inside which a product B is wrapped with the package film A. A package film tension adjusting device constructed in accordance with a first embodiment of the present invention, generally designated with reference numeral 100, is arranged between the film supply section 210 and the wrapping/sealing section 220.

[0019] In the embodiment illustrated, the film supply section 210 has a first longitudinal direction along which the film A is forwarded. The wrapping/tensioning section 220 has a second longitudinal direction along which the product B is conveyed. The first and second longitudinal directions are arranged to be substantially normal to each other. However, it is understood that the first and second longitudinal directions can be arranged in different way.

[0020] The package film tension adjusting device 100 comprises a chassis 10 inside which two spaced rails 20 are fixed. The rails 20 can be of any known type and are cylindrical rods in the embodiment illustrated. Two slide blocks 30 are movably supported on the rails 20 by bearing means 31 whereby the slide blocks 30 are movable along the rails 20. Stops 40 are arranged on opposite ends of the rails 20 for limiting the movement of the slide blocks 30 along the rails 20.

[0021] Also referring to FIG. 3, a locker unit 50 is mounted to at least one of the slide blocks 30 to releasably secure the slide block 30 at any desired location along the rails 20. The locker unit 50 comprises a collar 51 movably fit over one of the rails 20. A radially-extending, inner-threaded hole (not labeled) is defined in the collar 51 for threadingly engaging a threaded section 521 of a handle 52. The handle 52 allows a user to tighten the threaded section 521 with the inner-threaded hole of the collar 51 whereby a tip of the handle 52 engages the rail 20 to secure the slide block 30 is position.

[0022] A conveying device 60, such as a belt conveyor, is mounted on and carried by the slide blocks 30 for conveying the product B to be packaged into the wrapping/sealing section 220. The conveying device 60 comprises a pair of film routing members 61 arranged above and below the conveying device 60 respectively for changing the moving direction of the package film A so as to feed the package film A into the wrapping/sealing section 220. The conveying device 60 and the film routing members 61 are both known and thus no further detail is needed herein unless it is associated with the description of the present invention.

[0023] Also referring to FIG. 4, to operate, the locker unit 50 is released and the slide blocks 30 are moved along the rails 20 in a desired direction toward or away from the wrapping/sealing section 220 as indicated by dashed lines of FIG. 4. The movement of the slide blocks 30 relative to the wrapping/sealing section 220 changes the distance between the wrapping/sealing section 220 and the film routing members 61 thereby changing the tension of the package film A supplied from the film routing members 61 to the wrapping/sealing section 220. Since the slide blocks 30 are slidable along the rails 20, the distance between the wrapping/sealing section 220 and the film routing members 61 is adjusted in a stepless manner.

[0024] The locker unit 50 can be re-secured by rotating the handle 52 after the slide blocks 30 are moved to the desired position where the tension of the package film A is properly set. Securing the locker unit 50 prevents the slide blocks 30 and thus the conveying device 60 and the film routing members 61 from undesired movement along the rails 20 thereby effectively maintaining the tension of the package film A.

[0025]FIG. 5 shows a package film tension adjusting device constructed in accordance with a second embodiment of the present invention wherein a screw rod 80 threadingly engages inner-threaded holes 32 defined in the slide blocks 30. A hand wheel 70 is mounted to an end of the screw rod 80 for rotation of the screw rod 80. The rotation of the screw rod 80 causes the slide blocks 30 and thus the conveying device 60 and the film routing members 61 to move along the rails 20 whereby the distance between the routing members 61 and the wrapping/sealing section 220 is changed.

[0026]FIG. 6 show a package film tension adjusting device constructed in accordance with a third embodiment which is a modification of the second embodiment wherein the hand wheel 70 of the second embodiment is replaced by an electric motor 90. The operation of the electric motor 90 causes the screw rod 80 to rotate which leads to the movement of the slide blocks 30 along the rails 20 thereby changing the distance between the film routing members 61 and the wrapping/sealing section 220 and thus the tension of the package film A fed into the wrapping/sealing section 220.

[0027] The package film tension adjusting device of the present invention offers at least the following advantages:

[0028] (1) The stepless movement of the slide blocks 30 along the rails 20 allows the distance between the wrapping/sealing section 220 and the film routing members 61 to be changed in a stepless manner. The tension of the package film A that is fed into the wrapping/sealing section 220 by the film routing members 61 can thus be adjusted in a stepless manner whereby a proper tension of the package film A can be obtained for high quality package of the product B.

[0029] (2) The package film tension adjusting device 100 has a simple structure and thus low costs but is capable to achieve a precise adjustment of the film tension in a stepless manner. No sophisticated electronics is necessary and no calculation is required.

[0030] (3) The simple structure of the package film tension adjusting device 100 of the present invention allows it to be readily incorporated into both automatic packaging machines and semi-automatic packaging machines.

[0031] Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims. 

What is claimed is:
 1. A package film tension adjusting device adapted to be mounted between a supply of a package film and a wrapping/sealing section of a packaging machine, the package film tension adjusting device comprising rails on which slide blocks are movably supported for being movable relative to the wrapping/sealing section and thus changing distance therebetween, film routing means being mounted on the slide blocks to be movable therewith, the package film being fed into the wrapping/sealing section by the film routing means whereby moving the slide blocks along the rails changes the distance between the film routing means and the wrapping/sealing section and thus tension of the package film supplied from the film routing means to the wrapping/sealing section.
 2. The package film tension adjusting device as claimed in claim 1 further comprising stops arranged at opposite ends of the rails for limiting the movement of the slide blocks along the rails.
 3. The package film tension adjusting device as claimed in claim 1 further comprising a locker unit associated with at least one of the slide blocks for releasably securing the slide blocks at a desired position along the rails.
 4. The package film tension adjusting device as claimed in claim 3 wherein the locker unit comprises a collar slidably fit over one of the rails, an inner-threaded hole being defined in the collar for threadingly engaging a threaded section of a handle, the handle having an inner tip selectively engaging the rail for securing the slide block at the desired position along the rail.
 5. The package film tension adjusting device as claimed in claim 1 further comprising bearing means mounted between the slide blocks and the rails.
 6. The package film tension adjusting device as claimed in claim 1 further comprising a screw rod threadingly engaging inner-threaded holes defined in the slide blocks whereby rotation of the screw rod causes movement of the slide blocks along the rails.
 7. The package film tension adjusting device as claimed in claim 6 further comprising a device for rotating the screw rod.
 8. The package film tension adjusting device as claimed in claim 7, wherein the device for rotating the screw rod comprises a hand wheel.
 9. The package film tension adjusting device as claimed in claim 7, wherein the device for rotating the screw rod comprises an electric motor. 